Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Modelagem de cenários para o manejo sustentável de produtos florestais não-madeireiros em ecossistemas tropicais
    Bondé, Loyapin ; Assis, Julia Camara ; Benavides-Gordillo, Sandra ; Canales-Gomez, Erendira ; Fajardo, Javier ; Marrón-Becerra, Aurora ; Noguera-Urbano, Elkin A. ; Weidlich, Emanuela W.A. ; Ament, Judith M. - \ 2020
    Biota Neotropica 20 (2020)supl. 1. - ISSN 1676-0611 - 14 p.
    Biodiversity and Ecosystem Services - Conceptual model - Drivers of change - Shea tree - Tropical tree species

    Ecosystems degradation, and consequently biodiversity loss, has severe impacts on people around the world. The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) is one of the international initiatives that have emerged to inform policy makers and aid decisions to prevent further global biodiversity loss, focusing on the interdependence between natural systems and human culture. IPBES promotes the use of scenarios and modelling approaches as a fundamental tool to advance the understanding of the relationships between drivers of change, Nature’s Contributions to People (NCP), and social systems. Local-scale case studies with a system approach demonstrating how current knowledge can be used to inform decision-making are still scarce. Here, we present a comprehensive conceptual model and a series of four scenarios under different policies for shea tree species management, as a case-study of applying systems thinking and the NCP concept to a local-scale socio-ecological system. We first characterized the central processes, NCP, drivers and pressures affecting the shea tree system, to investigate the impacts of the multiple uses of the shea tree species on the system as a whole. We then described potential policy options, developed four scenarios, and evaluated them by a Bayesian Belief Network (BBN). We predicted qualitative outcomes of the proposed scenarios: Business-as-usual (BAU), “Conservation and fair trade”, “Agroforestry and fair trade” and “Industrial development”. We found that the scenarios focussing on conservation, fair trade and agroforestry, can improve the conservation status of shea trees, and enhance wellbeing in the local communities. In this case study, we demonstrate that the development of a comprehensive conceptual model at a local scale can be a useful exercise to identify opportunities for effective policy strategies and social innovation. The shea tree case study can provide an example for modelling non-timber forest products in other regions around the world that face similar drivers and pressures. Species for which this model could be adapted include Central and South American species such as the Brazilian nut (Bertholletia excelsa), cocoa (Theobroma cacao), andiroba (Carapa guianensis), açai (Euterpe oleracea) and the wax palm (Ceroxylon quindiuense). The model and workflow applied here may thus be used to understand similar socio-ecological systems with local and international economic value across the Neotropical region.

    Highly specific enrichment of rare nucleic acid fractions using Thermus thermophilus argonaute with applications in cancer diagnostics
    Song, Jinzhao ; Hegge, Jorrit W. ; Mauk, Michael G. ; Chen, Junman ; Till, Jacob E. ; Bhagwat, Neha ; Azink, Lotte T. ; Peng, Jing ; Sen, Moen ; Mays, Jazmine ; Carpenter, Erica L. ; Oost, John van der; Bau, Haim H. - \ 2020
    Nucleic acids research 48 (2020)4. - ISSN 0305-1048 - p. e19 - e19.

    Detection of disease-associated, cell-free nucleic acids in body fluids enables early diagnostics, genotyping and personalized therapy, but is challenged by the low concentrations of clinically significant nucleic acids and their sequence homology with abundant wild-type nucleic acids. We describe a novel approach, dubbed NAVIGATER, for increasing the fractions of Nucleic Acids of clinical interest Via DNA-Guided Argonaute from Thermus thermophilus (TtAgo). TtAgo cleaves specifically guide-complementary DNA and RNA with single nucleotide precision, greatly increasing the fractions of rare alleles and, enhancing the sensitivity of downstream detection methods such as ddPCR, sequencing, and clamped enzymatic amplification. We demonstrated 60-fold enrichment of the cancer biomarker KRAS G12D and ∼100-fold increased sensitivity of Peptide Nucleic Acid (PNA) and Xenonucleic Acid (XNA) clamp PCR, enabling detection of low-frequency (<0.01%) mutant alleles (∼1 copy) in blood samples of pancreatic cancer patients. NAVIGATER surpasses Cas9-based assays (e.g. DASH, Depletion of Abundant Sequences by Hybridization), identifying more mutation-positive samples when combined with XNA-PCR. Moreover, TtAgo does not require targets to contain any specific protospacer-adjacent motifs (PAM); is a multi-turnover enzyme; cleaves ssDNA, dsDNA and RNA targets in a single assay; and operates at elevated temperatures, providing high selectivity and compatibility with polymerases.

    Enrichment of nucleic acids
    Bau, Haim ; Song, Jinzhao ; Liu, Changchun ; Mauk, Michael ; Oost, J. van der; Hegge, J.W. - \ 2019
    Octrooinummer: WO2019178346, gepubliceerd: 2019-09-19.
    Provided are methods directed to enriching nucleic acids in a biological sample. These methods, in some embodiments can discriminately enrich the abundance of low-copy nucleic acids relative to higher-copy nucleic acids. In some embodiments, the methods provided can enrich a low-copy number mutant allele associated with a disease state, thus allowing early detection and optimized treatment. In other embodiments, the methods can be used for detection of particular molecules, such as antigens, in a sample.
    Exploring Future Food Provision Scenarios for China
    Ma, Lin ; Bai, Zhaohai ; Ma, Wenqi ; Guo, Mengchu ; Jiang, Rongfeng ; Liu, Junguo ; Oenema, Oene ; Velthof, Gerard L. ; Whitmore, Andrew P. ; Crawford, John ; Dobermann, Achim ; Schwoob, Marie ; Zhang, Fusuo - \ 2019
    Environmental Science and Technology 53 (2019)3. - ISSN 0013-936X - p. 1385 - 1393.

    Developing sustainable food systems is essential, especially for emerging economies, where food systems are changing rapidly and affect the environment and natural resources. We explored possible future pathways for a sustainable food system in China, using multiple environmental indicators linked to eight of the Sustainable Development Goals (SDGs). Forecasts for 2030 in a business as usual scenario (BAU) indicate increases in animal food consumption as well as increased shortages of the land available and the water needed to produce the required food in China. Associated greenhouse gas emissions and nitrogen and phosphorus losses could become 10-42% of global emissions in 2010. We developed three main pathways besides BAU [produce more and better food (PMB), consume and waste less food (CWL), and import more food (IMF)] and analyzed their impacts and contributions to achieving one or more of the eight SDGs. Under these scenarios, the demand for land and water and the emissions of GHG and nutrients may decrease by 7-55% compared to BAU, depending on the pathway followed. A combination of PMB and CWL was most effective, while IMF externalizes impacts to countries exporting to China. Modestly increasing feed or food imports in a selective manner could ease the pressure on natural resources. Our modeling framework allows us to analyze the effects of changes in food production-consumption systems in an integrated manner, and the results can be linked to the eight SDGs. Despite formidable technological, social, educational, and structural barriers that need to be overcome, our study indicates that the ambitious targets of China's new agricultural and environmental strategy appear to be achievable.

    Scenarios of Land Use and Land Cover Change and Their Multiple Impacts on Natural Capital in Tanzania
    Capitani, Claudia ; Soesbergen, Arnout van; Mukama, Kusaga ; Malugu, Isaac ; Mbilinyi, Boniface ; Chamuya, Nurdin ; Kempen, Bas ; Malimbwi, Rogers ; Mant, Rebecca ; Munishi, Panteleo ; Njana, Marco Andrew ; Ortmann, Antonia ; Platts, Philip J. ; Runsten, Lisen ; Sassen, Marieke ; Sayo, Philippina ; Shirima, Deo ; Zahabu, Elikamu ; Burgess, Neil D. ; Marchant, Rob - \ 2019
    Environmental Conservation 46 (2019)1. - ISSN 0376-8929 - p. 17 - 24.
    Reducing emissions from deforestation and forest degradation plus the conservation of forest carbon stocks, sustainable management of forests and enhancement of forest carbon stocks in developing countries (REDD+) requires information on land-use and land-cover changes (LULCCs) and carbon emission trends from the past to the present and into the future. Here, we use the results of participatory scenario development in Tanzania to assess the potential interacting impacts on carbon stock, biodiversity and water yield of alternative scenarios where REDD+ is or is not effectively implemented by 2025, a green economy (GE) scenario and a business as usual (BAU) scenario, respectively. Under the BAU scenario, LULCCs will cause 296 million tonnes of carbon (MtC) national stock loss by 2025, reduce the extent of suitable habitats for endemic and rare species (mainly in encroached protected mountain forests) and change water yields. In the GE scenario, national stock loss decreases to 133 MtC. In this scenario, consistent LULCC impacts occur within small forest patches with high carbon density, water catchment capacity and biodiversity richness. Opportunities for maximizing carbon emission reductions nationally are largely related to sustainable woodland management, but also contain trade-offs with biodiversity conservation and changes in water availability.
    Implementation of PROMETHEUS 4‐step approach for evidence use in EFSA scientific assessments: benefits, issues, needs and solutions
    Aiassa, Elisa ; Martino, Laura ; Barizzone, Fulvio ; Ciccolallo, Laura ; Garcia, Ana ; Georgiadis, Marios ; Guajardo, Irene Muñoz ; Tomcikova, Daniela ; Alexander, Jan ; Calistri, Paolo ; Gundert‐remy, Ursula ; Hart, Andrew David ; Hoogenboom, Ron Laurentius ; Messean, Antoine ; Naska, Androniki ; Navarro, Maria Navajas ; Noerrung, Birgit ; Ockleford, Colin ; Wallace, Robert John ; Younes, Maged ; Abuntori, Blaize ; Alvarez, Fernando ; Aryeetey, Monica ; Baldinelli, Francesca ; Barrucci, Federica ; Bau, Andrea ; Binaglia, Marco ; Broglia, Alessandro ; Castoldi, Anna Federica ; Christoph, Eugen ; Sesmaisons‐Lecarré, Agnes De; Georgiadis, Nikolaos ; Gervelmeyer, Andrea ; Istace, Frederique ; López‐Gálvez, Gloria ; Manini, Paola ; Maurici, Daniela ; Merten, Caroline ; Messens, Winy ; Mosbach‐Schulz, Olaf ; Putzu, Claudio ; Bordajandi, Luisa Ramos ; Smeraldi, Camilla ; Tiramani, Manuela ; Martínez, Silvia Valtueña ; Sybren, Vos ; Hardy, Anthony Richard ; Hugas, Marta ; Kleiner, Juliane ; Seze, Guilhem De - \ 2018
    EFSA Supporting Publications 15 (2018)4. - ISSN 2397-8325
    In 2014, the European Food Safety Authority (EFSA) started the PROMETHEUS (PROmoting METHods for Evidence Use in Scientific assessments) project to improve further and increase the consistency of the methods it uses in its scientific assessments. The project defined a set of principles for the scientific assessment process and a 4‐step approach (plan/carry out/verify/report) for their fulfilment, which was tested in ten case studies, one from each EFSA panel. The present report describes the benefits, issues, needs and solutions related to the implementation of the 4‐step approach in EFSA, identified in a dedicated workshop in October 2017. The key benefits of the approach, which was deemed applicable to all types of EFSA scientific assessment including assessments of regulated products, are: 1) increased ‘scientific value’ of EFSA outputs, i.e. the extent of impartiality, methodological rigour, transparency and engagement; 2) guarantee of fitness‐for‐purpose, as it implies tailoring the methods to the specificities of each assessment; 3) efficiency gain, since preparing a protocol for the assessment upfront helps more streamlined processes throughout the implementation phase; 4) innovation, as the approach promotes the pioneering practice of ‘planning before doing’ (well established in primary research) for broad scientific assessments in regulatory science; and 5) increased harmonisation and consistency of EFSA assessments. The 4‐step approach was also considered an effective system for detecting additional methodological and/or expertise needs and a useful basis for further defining a quality management system for EFSA's scientific processes. The identified issues and solutions related to the implementation of the approach are: a) lack of engagement and need for effective communication on benefits and added value; b) need for further advances especially in the field of problem formulation/protocol development, evidence appraisal and evidence integration; c) need for specialised expertise in the previous aspects; and specific needs for d) assessments of regulated products and e) outsourced projects.
    Assessment of possible solid-phase phosphate sorbents to mitigate eutrophication : Influence of pH and anoxia
    Mucci, Maíra ; Maliaka, Valentini ; Noyma, Natalia Pessoa ; Marinho, Marcelo Manzi ; Lürling, Miquel - \ 2018
    Science of the Total Environment 619-620 (2018). - ISSN 0048-9697 - p. 1431 - 1440.
    Geo-engineering - Phosphate adsorption - Phosphorus control

    Managing eutrophication remains a challenge to water managers. Currently, the manipulation of biogeochemical processes (i.e., geo-engineering) by using phosphorus-adsorptive techniques has been recognized as an appropriate tool to manage the problem. The first step in finding potential mitigating materials is conducting a sequence of upscaling studies that commence with controlled laboratory experiments. Here, the abilities of 10 possible solid–phase-sorbents (SPS) to adsorb P were examined. Four materials adsorbed P, and two of these materials were modified, i.e., a lanthanum-modified-bentonite (LMB) and an aluminum-modified-zeolite (AMZ), and had the highest adsorption capacities of 11.4 and 8.9 mg P g− 1, respectively. Two natural materials, a red soil (RS) and a bauxite (BAU), were less efficient with adsorption capacities of 2.9 and 3.4 mg P g− 1, respectively. Elemental composition was not related to P adsorption. Since SPS might be affected by pH and redox status, we also tested these materials at pH values of 6, 7, 8 and 9 and under anoxic condition. All tested materials experienced decreased adsorption capacities under anoxic condition, with maximum adsorptions of 5.3 mg P g− 1 for LMB, 5.9 mg P g− 1 for AMZ, 0.2 mg P g− 1 for RS and 0.2 mg P g− 1 for BAU. All materials were able to adsorb P across the range of pH values that were tested. The maximum adsorption capacities of LMB and RS were highest at pH 6, AMZ was higher at a pH of 9 and BAU at a pH of 8. Thus, pH influenced P adsorption differently. Given the effects of pH and anoxia, other abiotic variables should also be considered. Considering the criteria that classify a useful SPS (i.e., effective, easy to produce, cheap and safe), only the two modified materials that were tested seem to be suitable for upscaling to enclosure studies with anoxic sediments.

    Modeling soil acidification in typical Chinese cropping systems
    Zhu, Qichao ; Liu, Xuejun ; Hao, Tianxiang ; Zeng, Mufan ; Shen, Jianbo ; Zhang, Fusuo ; Vries, Wim De - \ 2018
    Science of the Total Environment 613-614 (2018). - ISSN 0048-9697 - p. 1339 - 1348.
    China - Cropland - Mitigation - Scenarios - Soil acidification - VSD + model

    We applied the adapted model VSD + to assess cropland acidification in four typical Chinese cropping systems (single Maize (M), Wheat-Maize (W-M), Wheat-Rice (W-R) and Rice-Rice (R-R)) on dominant soils in view of its potential threat to grain production. By considering the current situation and possible improvements in field (nutrient) management, five scenarios were designed: i) Business as usual (BAU); ii) No nitrogen (N) fertilizer increase after 2020 (N2020); iii) 100% crop residues return to cropland (100%RR); iv) manure N was applied to replace 30% of chemical N fertilizer (30%MR) and v) Integrated N2020 and 30%MR with 100%RR after 2020 (INMR). Results illustrated that in the investigated calcareous soils, the calcium carbonate buffering system can keep pH at a high level for > 150 years. In non-calcareous soils, a moderate to strong decline in both base saturation and pH is predicted for the coming decades in the BAU scenario. We predicted that approximately 13% of the considered croplands may suffer from Al toxicity in 2050 following the BAU scenario. The N2020, 100%RR and 30%MR scenarios reduce the acidification rates by 16%, 47% and 99%, respectively, compared to BAU. INMR is the most effective strategy on reducing acidification and leads to no Al toxicity in croplands in 2050. Both improved manure and field management are required to manage acidification in wheat-maize cropping system.

    Exploring nutrient management options to increase nitrogen and phosphorus use efficiencies in food production of China
    Wang, Mengru ; Ma, Lin ; Strokal, Maryna ; Chu, Yanan ; Kroeze, Carolien - \ 2018
    Agricultural Systems 163 (2018). - ISSN 0308-521X - p. 58 - 72.
    Fertilizer policy - Food production - N and P losses - N and P use efficiency - Nutrient management

    Low nitrogen (NUE) and phosphorus (PUE) use efficiencies in food production in China result in large losses of nitrogen (N) and phosphorus (P) to the environment. The Chinese government formulated policies to increase the NUEs and PUEs. Recent policies aim for zero growth in synthetic fertilizer use after 2020 while ensuring food security. In this study we analyzed how current and improved nutrient management in China can affect future nutrient use efficiencies and nutrient losses from food production. The NUEs and PUEs of food production were quantified using the NUFER (NUtrient flows in Food chains, Environment and Resources use) model for 31 provinces and China in 2013, 2020 and 2050. Results show that national NUE (20%) and PUE (24%) in 2013 are low but vary largely among provinces (12-33% for NUE, 10-53% for PUE). The N and P losses to the air (14Tgyear-1 of N) and waters (12Tgyear-1 of N, 2Tgyear-1 of P) are consequently high in 2013. Three scenarios were analyzed for 2020 and 2050 to explore future trends in NUEs and PUEs, assuming Business As Usual (BAU) trends, Zero Fertilizer (ZF) growth from 2020, and Improved Nutrient Management (INM). In the BAU scenario, the NUEs and PUEs roughly remain at their low 2013 levels, while nutrient inputs to agriculture are increasing. The losses to the air therefore increase by 37% for N and to waters by 40% for N and 48% for P between 2013 and 2050. In the ZF scenario, the NUEs and PUEs are a few percent higher than in BAU. The associated N and P losses to waters are 8-16% lower than in BAU because of increased recycling of manure to cropland, but still higher than in 2013. Improved nutrient management, as assumed in our INM scenario, may increase NUEs and PUEs to 33% and 59% in 2050. Meanwhile, N and P losses to waters in 2050 are 47% and 83% lower than in 2013, and losses of N to the air 20% lower. We conclude that the policy aimed at zero growth in fertilizer use is a good start, but not very effective in reducing nutrient pollution in China. To substantially reduce N and P losses to the environment it is needed to improve nutrient management by not only reducing fertilization without yield losses, but also by improved manure management and animal production with lower nutrient excretion.

    The stability and effectiveness of international climate agreements : the role of carbon trade, bargaining power and enforcement
    Yu, Shumin - \ 2017
    Wageningen University. Promotor(en): E.C. van Ierland, co-promotor(en): H.P. Weikard; X. Zhu. - Wageningen : Wageningen University - ISBN 9789463430647 - 146

    Relying on individual countries’ efforts to reduce greenhouse gas (GHG) emissions is insufficient for keeping the rising global average temperature below a level detrimental to humans. Instead, the threat of climate change requires global cooperative efforts to reach significant reductions in GHG emissions. Yet, it is difficult to reach a consensus on sharing the burden of climate change mitigation among nation states because of the free-riding incentives resulting from the public good property of climate change mitigation. In the absence of a supranational agency that takes the role of an enforcer of commitments, the compliance with mitigation commitments is also an obstacle to mitigation cooperation even after an international climate agreement (ICA) has been signed and ratified. To enable effective GHG emissions mitigation, the design of institutional and economic instruments that can facilitate the formation of ICAs is needed. The aim of this thesis is therefore to study the stability and effectiveness of ICAs by considering the impacts of carbon trade, countries’ uneven bargaining powers and enforcement mechanisms. Game theoretical modelling is a useful and appropriate tool to study the incentive mechanisms applied to agents with different preferences, and is often used to study the formation and stability of ICAs. Hence, game theory applies throughout this thesis. To relate the analytical solutions to the real problems in ICAs formation and thus to provide policy insights, numerical models and analyses are also employed and presented in this thesis.

    While Chapter 1 sets the scene and formulates the research questions, Chapter 2 develops a four-stage coalition formation game in order to study the impact of a carbon market on regional incentives to join an ICA for GHG emissions mitigation when the carbon market is established independently of this agreement. This carbon market, which is assumed to be formed after the mitigation coalition, is open to the mitigation coalition and its outsiders. In particular, the initial emissions permit choice of each participant in the carbon market is based on an endogenous permit choice mechanism introduced by Helm (2003). The impact of this carbon market on incentives to join the mitigation coalition and the interlinkages between the two coalitions are studied. Results show that number and size of stable mitigation coalitions are smaller with than without a carbon market. The intuition is that in the presence of a carbon market, players are faced with more strategic choices implying that members of the stable mitigation coalitions have a potential incentive to deviate from a mitigation coalition and become a carbon trader instead. This can destabilise the mitigation coalition. Because the carbon market offers an alternative or complementary policy instrument to facilitate mitigation, some non-signatories to the mitigation coalition would join a carbon market which helps to reduce global emissions. However, the mitigation coalition has no incentive to join a carbon market with non-signatories, since the benefits from free riding surpass the net gains from carbon trade. It is concluded that even with this dual-agreement system, free-riding incentives prevail and global cooperation does not emerge.

    Chapter 3 develops a model of an international carbon market where allowances are endogenously determined by each member of a carbon trade agreement, but with an exogenous constraint on the number of allowances per member. A global model is used to explore the incentives for regions to participate in such a carbon market and to examine its performance. Results show that the stability and effectiveness of an international carbon market can be improved by imposing constraints on individual allowance choices compared to a carbon market without such constraints. Constraints on allowance choices reduce “hot air” and increase global welfare and mitigation. Under a relatively lax constraint (12% below BAU emissions in the STACO calibration), a carbon market with the largest membership can be formed. When tightening the constraint the stable carbon markets become smaller but perform better in terms of global abatement and welfare. If the constraint is too tight, however, no stable carbon market can be formed. Moreover, numerical results also demonstrate that by tying individual allowance choice constraints to the Nash-emissions levels, international carbon markets are more successful in terms of global welfare and abatement, as it responds better to individual incentives to participate. Hence, a revision of the baseline could ease current climate negotiations, where BAU emissions are still dominant for defining and negotiating abatement targets or emission allowances.

    Chapter 4 studies the impact of using the Nash bargaining solution (NBS) for distributing coalitional gains under different sets of bargaining weights on the stability and effectiveness of international climate agreements. International climate negotiations are modelled as a Nash bargaining game in which cooperative gains are distributed based on the NBS with asymmetric bargaining power. In climate negotiations, asymmetric countries’ bargaining powers are unequal and may be driven by different characteristics of the players. By discussing and reviewing potential reasons that could induce differences of negotiators’ bargaining power in international climate negotiations, five different factors that determine negotiators’ bargaining power are identified: i) discount factor; ii) abatement efforts; iii) abatement costs; iv) climate change damages; v) economic power. Numerical results illustrate that the Nash bargaining solution can improve the participation incentives and performances of ICAs as compared to those that do not redistribute gains from cooperation, but its capacity to overcome free-riding incentives is limited. The success of international climate agreements depends on the set of bargaining weights that matters in climate negotiation. Among five sets of asymmetric bargaining weights, the one determined by negotiators’ economic power can facilitate a climate coalition that comprises two of the largest emitters (China and United States) jointly with two other regions (High Income Asia countries and Brazil). In climate policy making multiple determinants of bargaining power will play a role. This is because countries’ incentives to cooperate on GHG mitigation are impacted in a complex way by factors that are related to abatement options, climate change vulnerability and economic power. Hence, the bargaining power of each negotiator is likely to be driven by multiple determinants. Our model can be extended in a straightforward manner to account for different interlinked drivers of bargaining power if these can be determined.

    Chapter 5 studies the design of an optimal enforcement mechanism for a self-enforcing ICA and the impact of an optimally designed enforcement mechanism on participation and compliance. The model is formulated as a sequential cartel formation game, in which the coalition chooses an enforcement policy comprising an abatement target, monitoring expenditures and fines. Individual signatories respond by choosing their preferred abatement level which may or may not comply with the target. In equilibrium, signatories’ compliance levels are determined by individual welfare maximization under the agreed enforcement policy. Considering partial compliance, it is demonstrated that the extent of compliance depends on abatement targets, monitoring expenditures (the intensity of monitoring) and the fine. Results show that the compliance level of a coalition member can always be improved by increasing the monitoring expenditure. However, the effect of the target on compliance levels depends on the structure of the fine function. The coalitional best abatement level can be induced as a joint result of the monitoring expenditure and the target when the fine function is quadratic. Because monitoring is costly, full compliance will usually not be enforced. As to the stability, a “broad” and “deep” climate coalition cannot be formed with a costly enforcement mechanism.

    Four conclusions can be drawn from this thesis. First, establishing a carbon market outside of a mitigation coalition may not help to improve countries’ incentives to join the mitigation coalition, while the global mitigation level can be increased because the carbon market offers an alternative or complementary policy instrument to facilitate mitigation. Second, imposing a constraint with moderate degrees of strictness on initial allowance choices can increase the mitigation effectiveness and participation level of an international carbon market. Moreover, changing the baseline of the constraint from the BAU emissions level to the non-cooperative Nash level can also be considered a way to improve the success of an international carbon market. Third, factors that could influence bargaining powers of negotiating countries can be brought up and determined at pre-stage of international climate negotiations. Hence, policy designers for negotiations of ICAs may consider to use the determinants of bargaining power that can enhance large emitters’ bargaining position to improve the mitigation effectiveness of ICAs. Fourth, due to the existence of free-riding incentives in the process of compliance with mitigation commitments, an optimally designed enforcement policy is needed for the successful implementation of ICAs.

    Improving environmental sustainability of Thai palm oil production in 2050
    Saswattecha, Kanokwan ; Kroeze, Carolien ; Jawjit, Warit ; Hein, Lars - \ 2017
    Journal of Cleaner Production 147 (2017). - ISSN 0959-6526 - p. 572 - 588.
    Environmental impact - Land-use-change - Palm oil - Scenario analysis - Sustainability - Thailand

    Palm oil production has increased in Thailand with considerable environmental impacts. The aim of this study is to analyse possibilities to examine how the environmental sustainability of Thai palm oil production can be improved in the coming decades. To this end, we integrated a sectoral and a landscape model in order to analyse scenarios for 2050. We do this with a focus on options to reduce (1) the effects of land-use-change on ecosystem services, and (2) the environmental impact of oil palm plantations and palm oil mills. Four future scenarios are developed; business-as-usual (BAU), current-policy (CP), strong-growth (GRT) and green-development (GRN). The BAU scenario indicates that environmental impacts may double without additional improvement options. The CP scenario shows that current plans to increase palm oil production would considerably increase environmental impacts. Implementing only cost-effective options, as in the GRT scenario, is also not enough to avoid an increase in environmental impacts if the export of palm oil increases faster than currently envisaged. The GRN scenario assumes implementation of a combination of effective options, regardless of their costs. This would considerably reduce environmental impacts. Thus it is technically possible to improve environmental performance of palm oil production in Thailand.

    Improving Nitrogen Use Efficiency in the Chinese Food Chain to Reduce Air and Water Pollution
    Wang, M. ; Ma, L. ; Strokal, M. ; Chu, Yayan ; Li, Ang ; Kroeze, C. - \ 2016
    Nitrogen (N) use efficiency is low in Chinese agriculture. This results in large N losses to air and water. We aim to explore effective nutrient management options to increase N use efficiencies in the food chain, and thus to reduce N losses to the environment for 2020 and 2050 in China by scenario analysis. Three scenarios were developed and implemented assuming Business As Usual (BAU) trends, Zero Fertilizer (ZF) growth from 2020, and Improved Nutrient Management (INM). N use efficiencies in agriculture, and N losses were
    quantified using the NUFER (NUtrient flows in Food chains, Environment and Resources use) model. Results show that N use efficiency in 2013 is low at about 20%. Thus the losses to air (14 Tg of N) and water (12 Tg of N) are high in 2013. The N use efficiencies will likely remain at their low 2013 levels in 2020 and
    2050 under BAU, resulting in large increase in N losses to air and water between 2013 and 2050. INM is projected to increase N use efficiency to 33% in 2050. N losses to water in 2050 are almost half of that in 2013, and to air are 20% lower. Scenario ZF incorporates recent Chinese policies aiming at a zero growth in
    synthetic fertilizer use from the year 2020 onwards. ZF is projected to be much less effective than INM. We conclude that nutrient management that simultaneously reduces fertilization, improves manure management,
    and reduces nutrient excretion in animal manure, is needed for Chinese agriculture.
    Impacts of dietary changes on global scale nitrogen losses to air and water
    Vries, W. de; Wei, Jia ; Kros, J. ; Windhorst, David ; Breuer, Lutz - \ 2016
    A simple fast calculation approach has been developed that gives insight in the overall effects of dietary changes on nitrogen (N) emission to air and water by 2050 for ten identified world regions. The impact of dietary change on N fertilizer and N manure applications and related emissions was based on the consumption of crop and animal commodities, making use of the FAO data from 1961 to 2005 and extrapolating the data towards 2050 in response to five dietary change scenarios. Scenarios included a ‘North American Diet’ (NAD), a ‘Same Diet’ (SD), a ‘Business-as-Usual’ (BAU) diet; a ‘Demitarian Diet’ (DD) and a ‘Vegan Diet’ (VD). The calculated N2O and NH3 emissions and N leaching/runoff for the reference year (i.e. 2005) showed good agreement with various literature estimates. N2O was the most persistent problem, even increasing under the VD scenario, due to the increased use of N fertilizer to cultivate food crops and the assumed high contribution of N fertilizer to N2O emission. NH3 emissions increased three times in the NAD scenario, while it decreased by 13% in the VD scenario. This happens because NH3 emissions mainly follow the N manure trends. In the VD scenario, N leaching/runoff remains equal to 2005, while it increases by 145% in the NAD scenario. Overall, results show that dietary change affects most strongly NH3 emissions, followed by N leaching/runoff and then N2O emissions. Only a severe reduction in meat consumption can substantially reduce N losses with the exception of N2O emissions.
    Super-performance in a palm species
    Jansen, Merel - \ 2016
    Wageningen University. Promotor(en): Niels Anten; Pieter Zuidema, co-promotor(en): Frans Bongers; M. Martínez-Ramos. - Wageningen : Wageningen University - ISBN 9789462579996 - 193
    chamaedorea elegans - understorey - tropical forests - spatial variation - leaves - growth - population ecology - defoliation - genetic variation - chamaedorea elegans - onderlaag - tropische bossen - ruimtelijke variatie - bladeren - groei - populatie-ecologie - ontbladering - genetische variatie

    The world is changing rapidly due to anthropogenic disturbance. Effects include: global warming, massive pollution, a changed global nitrogen cycle, high rates of land-use change, and exotic species spread. This has a tremendous impact on both natural and agricultural systems. To understand these impacts, good understanding of ecological systems and underlying drivers is necessary. Ecological systems can be studied at different levels of aggregation. Different levels of aggregation influence each other and are also influenced by external drivers like the environment. The population level is of particular interest, because many important ecological processes occur at the population level, like evolution, extinction, and invasion. Ecologists are increasingly recognizing that population processes are strongly influenced by one level of aggregation lower, the individual level. Individual heterogeneity (i.e. differences between individuals in performance), determines many population processes including population growth rate. However, the exact relations between individual heterogeneity, the external drivers of it, and the population level are not always well understood. Furthermore, methods to analyze these relations are not always available.

    Individual heterogeneity occurs at different temporal scales, ranging from short- to long-term performance differences between individuals, where short- and long-term refer to the expected lifespan of the species in question. Short-term differences between individuals are relatively easily identifiable and are common in almost all species. But long-term differences are much harder to determine especially for long-lived organisms. Long-term differences between individuals in reproduction have been identified for several animal species, and in growth for several tree species, but less is known about the existence of such differences in other life forms (e.g. palms, lianas or clonal plants). Quantifying the extent to which individuals differ is essential for understanding the influence of individual heterogeneity on population processes. Super-performing individuals (i.e. individuals that persistently grow faster and reproduce more than others), probably contribute more to the growth of the population and therefore to future generations. Future populations will, therefore, have the genetic characteristics of the super-performers. Which characteristics this will be, depends on the genetic and environmental drivers of super-performance. Full understanding of the influence of individual heterogeneity on population processes, therefore, requires knowledge of the underlying causes of individual heterogeneity.

    For many species, it is known that spatial variation in environmental conditions can cause short-term performance differences between individuals, but it is often not clear if the same environmental factors that cause short-term performance differences are also the environmental factors that cause long-term performance differences. Furthermore, genetic variation is known to cause performance differences, but to what extent is not well studied in natural long-lived plant populations. Within-population genetic variation can be maintained in habitats that are characterized by strong temporal or spatial heterogeneity in environmental conditions if the performance of a genotype relative to others depends on the environment it experiences.

    Super-performing individuals possibly play an important role in the resistance and resilience of populations to disturbance (i.e. maintaining and recovering population growth rate under stress), because super-performers potentially contribute more to the recovery of the population. However, this depends on the relative tolerance to disturbance of super-performers compared to under-performers. A positive relation between performance and tolerance would make super-performers more important, while a negative relation would make them less important. Many types of disturbances entail leaf loss and tolerance to leaf loss is associated with performance being larger than what one would assume based on the amount of leaf area loss. Tolerance can be achieved by compensating for leaf loss in terms of growth rate, which entails either allocating more new assimilates to leaves, allocating new assimilates more efficiently to leaf area (i.e. by increasing specific leaf area), or growing faster with existing leaf area (i.e. by increasing net assimilation rate). Genetic variation in tolerance and compensatory responses would allow populations to adapt to changes in disturbance events that entail leaf loss.

    Individual heterogeneity could also have implications for management. Plant and animal populations are managed at many different levels ranging from harvest from natural populations to modern agricultural practices. When harvesting from natural populations, it might be beneficial to spare the individuals that are most important for future production. Individuals could be spared, either because they contribute most to population growth, because they are tolerant to harvesting (which is relevant when only part of a plant is harvested), or when they start producing less or lower quality product. The productivity of natural populations could also be increased by actively promoting those environmental conditions and genotypes that allow for high productivity, which is the basis of agriculture and common practice in forest management. To determine how this can best be done, knowledge of the causes of individual heterogeneity is necessary.

    The general aim of this thesis is to identify and quantify the mechanisms that determine individual heterogeneity and to determine how this heterogeneity, in turn, affects population level processes. This aim was divided into four main questions that I addressed: (1) To what extent do individuals differ in performance? (2) What causes individual heterogeneity in performance? (3) What are the demographic consequences of individual heterogeneity? (4) Can individual differences be used to improve the management of populations? To answer these questions, we used the tropical forest understorey palm Chamaedorea elegans as a study system, of which the leaves are an important non-timber forest product that is being used in the floral industry worldwide. We collected demographic data, measured spatial variation in environmental conditions, and applied a defoliation treatment to simulate leaf harvesting, in a natural population in Chiapas, Mexico. Furthermore, we grew seedlings from different mothers from our study population in the greenhouses of Wageningen University, where we also applied a defoliation treatment.

    In Chapter 2 we quantified the extent to which individuals differ in long-term growth rate, and analyzed the importance of fast growers for population growth. We reconstructed growth histories from internodes and showed that growth differences between individuals are very large and persistent in our study population. This led to large variation in life growth trajectories, with individuals of the same age varying strongly in size. This shows that not only in canopy trees but also in species in the light limited understorey growth differences can be very large. Past growth rate was found to be a very good predictor of current performance (i.e. growth and reproduction). Using an Integral Projection Model (i.e. a type of demographic model) that was based on size and past growth rate, we showed that fast-growing individuals are much more important for population growth than others: the 50% fastest growing individuals contributed almost two times as much to population growth as the 50% slowest growing individuals.

    In Chapter 3 we analyzed the extent to which observed long-term growth differences can be caused by environmental heterogeneity. Short-term variation in performance was mainly driven by light availability, while soil variables and leaf damage had smaller effects, and spatial heterogeneity in light availability and soil pH were autocorrelated over time. Using individual-based simulation models, we analyzed the extent to which spatial environmental heterogeneity could explain observed long-term variation in growth, and showed that this could largely be explained if the temporal persistence of light availability and soil pH was taken into account. We also estimated long-term inter-individual variation in reproduction to be very large. We further analyzed the importance of temporal persistence in environmental variation for long-term performance differences, by analyzing the whole range of values of environmental persistence, and the strength of the effect of the environmental heterogeneity on short-term performance. We showed that long-term performance differences become large when either the strength of the effect of the environmental factor on short-term performance is large, or when the spatial variation in the environmental factor is persistent over time. This shows that an environmental factor that in a short-term study might have been dismissed as unimportant for long-term performance variation, might, in reality, contribute strongly.

    In Chapter 4 we tested for genetic variation in growth potential, tolerance to leaf loss, compensatory growth responses, and if growth potential and tolerance were genetically correlated in our study population. We quantified compensatory responses with an iterative growth model that takes into account the timing of leaf loss. Genetic variation in growth potential was large, and plants compensated strongly for leaf loss, but genetic variation in tolerance and compensatory growth responses was very limited. Growth performances in defoliated and undefoliated conditions were positively genetically correlated (i.e. the same genotypes perform relatively well compared to others, both with and without the stress of leaf loss). The high genetic variation in growth potential and the positive correlation between treatments suggests that the existence of super-performing individuals in our study population likely has (at least in part) a genetic basis. These super-performing individuals, that grow fast even under the stress of leaf loss, possibly contribute disproportionately to population resistance and resilience to disturbance. The low genetic variation in tolerance and compensatory responses, however, suggests that populations might have limited ability to adapt to changes in disturbance regimes that entail increases in leaf loss. Furthermore, the high genetic variation in growth potential could potentially be used in management practices like enrichment planting.

    In Chapter 5 we explore the potential of using individual heterogeneity to design smarter harvest schemes, by sparing individuals that contribute most to future productivity. We tested if fast and slow growers, and small and large individuals, responded differently to leaf loss in terms of vital rates, but found only very limited evidence for this. Using Integral Projection Models that were based on stem length and past growth rate, we simulated leaf harvest over a period of 20 years, in several scenarios of sparing individuals, which we compared to “Business as usual” (i.e. no individuals being spared, BAU). Sparing individuals that are most important for population growth, was beneficial for population size (and could, therefore, reduce extinction risk), increased annual leaf harvest at the end of the simulation period, but cumulated leaf harvest over 20 years was much lower compared to BAU. Sparing individuals that produced leaves of non-commercial size (i.e. <25cm), therefore allowing them to recover, also resulted in a lower total leaf harvest over 20 years. However, a much higher harvest (a three-fold increase) was found when only leaves of commercial size were considered. These results show that it is possible to increase yield quality and sustainability (in terms of population size) of harvesting practices, by making use of individual heterogeneity. The analytical and modeling methods that we present are applicable to any natural system from which either whole individuals, or parts of individuals, are harvested, and provide an extra tool that could be considered by managers and harvest practitioners to optimize harvest practices.

    In conclusion, in this thesis, I showed that in a long-lived understorey palm growth differences are very large and persistent (Chapter 2) and that it is likely that long-term differences in reproduction are also very large (Chapter 3). I also showed that spatial heterogeneity in environmental conditions can to a large extent explain these differences and that when evaluating the environmental drivers of individual heterogeneity, it is important to take the persistence of spatial variation into account (Chapter 3). Individual heterogeneity also is partly genetically determined. I showed that genetic variation in growth potential to be large (Chapter 4), and that fast growers keep on growing fast under the stress of leaf loss (Chapters 4,5). Therefore it is likely that genetic variation contributes to long-term differences between individuals. Genetic variation for tolerance and compensatory responses was estimated to be low (Chapter 4), suggesting that the adaptive potential of our study population to changes in disturbance events that entail leaf loss might be low. I also showed that super-performing individuals are much more important for the growth of the population (Chapter 2) and that individuals that are important for future production could be used to improve the management of natural populations (Chapter 5).

    This study provides improved insight into the extent of individual heterogeneity in a long-lived plant species and its environmental and genetic drivers, and clearly shows the importance of individual heterogeneity and its drivers for population processes and management practices. It also presents methods on how persistent performance differences between individuals can be incorporated into demographic tools, how these can be used to analyze individual contributions to population dynamics, to extrapolate short-term to long–term environmental effects, and to analyze smart harvesting scenarios that take differences between individuals into account. These results indicate that individual heterogeneity, underlying environmental and genetic drivers, and population processes are all related. Therefore, when evaluating the effect of environmental change on population processes, and in the design of management schemes, it is important to keep these relations in mind. The methodological tools that we presented provide a means of doing this.

    Projecting Global Biodiversity Indicators under Future Development Scenarios
    Visconti, Piero ; Bakkenes, Michel ; Baisero, Daniele ; Brooks, Thomas ; Butchart, Stuart H.M. ; Joppa, Lucas ; Alkemade, Rob ; Marco, Moreno Di; Santini, Luca ; Hoffmann, Michael ; Maiorano, Luigi ; Pressey, Robert L. ; Arponen, Anni ; Boitani, Luigi ; Reside, April E. ; Vuuren, Detlef P. van; Rondinini, Carlo - \ 2016
    Conservation Letters 9 (2016)1. - ISSN 1755-263X - p. 5 - 13.
    Biodiversity indicators - Biodiversity scenarios - Carnivores - Climate change - Extinction risk - Geometric Mean Abundance - Land-use change - Red List Index - Ungulates

    To address the ongoing global biodiversity crisis, governments have set strategic objectives and have adopted indicators to monitor progress toward their achievement. Projecting the likely impacts on biodiversity of different policy decisions allows decision makers to understand if and how these targets can be met. We projected trends in two widely used indicators of population abundance Geometric Mean Abundance, equivalent to the Living Planet Index and extinction risk (the Red List Index) under different climate and land-use change scenarios. Testing these on terrestrial carnivore and ungulate species, we found that both indicators decline steadily, and by 2050, under a Business-as-usual (BAU) scenario, geometric mean population abundance declines by 18-35% while extinction risk increases for 8-23% of the species, depending on assumptions about species responses to climate change. BAU will therefore fail Convention on Biological Diversity target 12 of improving the conservation status of known threatened species. An alternative sustainable development scenario reduces both extinction risk and population losses compared with BAU and could lead to population increases. Our approach to model species responses to global changes brings the focus of scenarios directly to the species level, thus taking into account an additional dimension of biodiversity and paving the way for including stronger ecological foundations into future biodiversity scenario assessments.

    Potential impacts on sub-Saharan Africa of reducing food loss and waste in the European Union : A focus on food prices and price transmission effects
    Rutten, M.M. ; Mhlanga, Nomathemba - \ 2015
    FAO - ISBN 9789251090282 - 64
    food consumption - food policy - food wastes - food prices - africa - europe - european union - voedselconsumptie - beleid inzake voedsel - voedselafval - voedselprijzen - afrika - europa - europese unie
    This paper investigates, by means of scenario analyses, how reductions in food loss and waste in the European Union (EU) could influence prices in sub-Saharan Africa – as a source and destination of traded agricultural and food products. Four 50 percent reduction scenarios are enacted, using the Modular Applied GeNeral Equilibrium Tool (MAGNET), in addition to a baseline “business as usual” (BaU) scenario. The analysis provides insights on potential impacts in terms of medium- to long-term global and local price changes in sub-Saharan Africa and the mechanisms behind them (changes in production, consumption and trade patterns). It also provides insights in terms of potential welfare impacts.
    Reducing nitrous oxide emissions from the global food system
    Oenema, O. ; Ju, X. ; Klein, C. de; Lesschen, J.P. ; Velthof, G.L. ; Kroeze, C. - \ 2014
    Current Opinion in Environmental Sustainability 9-10 (2014). - ISSN 1877-3435 - p. 55 - 64.
    phosphorus use efficiencies - greenhouse-gas emissions - n2o emissions - environmental-quality - fertilizer nitrogen - agricultural soils - management - china - crops - mitigation
    The global food system is a main source of nitrous oxide (N2O), estimated at 4.1–4.4 Tg N2O-N for 2010. Here, we review this source and assess its mitigation potential. Five mitigation strategies were explored and compared to a ‘business as usual’ (BAU) scenario: firstly, improved crop production; secondly, improved animal production; thirdly, improved manure management; fourthly improved food utilization; and finally, less animal-derived protein in diets. In the BAU scenario, emissions increased to 6.4 Tg for 2030 and 7.5 Tg for 2050. Emission reduction strategies could potentially reduce emissions to 4.1 Tg in 2030 and to 3.3 Tg in 2050, but there is considerable uncertainty in these estimates. In conclusion, packages of coherent strategies may offset the projected increases in N2O emissions from the global food system.
    Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi
    Schoch, C.L. ; Robbertse, B. ; Robert, V. ; Vu, D. ; Cardinali, G. ; Irinyi, L. ; Meyer, W. ; Nilsson, R.H. ; Hughes, K. ; Miller, A.N. ; Kirk, P.M. ; Abarenkov, K. ; Aime, M.C. ; Ariyawansa, H.A. ; Bidartondo, M. ; Boekhout, T. ; Buyck, B. ; Cai, Q. ; Chen, J. ; Crespo, A. ; Crous, P.W. ; Damm, U. ; Beer, Z.W. de; Dentinger, B.T.M. ; Divakar, P.K. ; Duenas, M. ; Feau, N. ; Fliegerova, K. ; Garcia, M.A. ; Ge, Z.W. ; Griffith, G.W. ; Groenewald, J.Z. ; Groenewald, M. ; Grube, M. ; Gryzenhout, M. ; Gueidan, C. ; Guo, L. ; Hambleton, S. ; Hamelin, R. ; Hansen, K. ; Hofstetter, V. ; Hong, S.B. ; Houbraken, J. ; Hyde, K.D. ; Inderbitzin, P. ; Johnston, P.A. ; Karunarathna, S.C. ; Koljalg, U. ; Kovacs, G.M. ; Kraichak, E. ; Krizsan, K. ; Kurtzman, C.P. ; Larsson, K.H. ; Leavitt, S. ; Letcher, P.M. ; Liimatainen, K. ; Liu, J.K. ; Lodge, D.J. ; Luangsa-ard, J.J. ; Lumbsch, H.T. ; Maharachchikumbura, S.S.N. ; Manamgoda, D. ; Martin, M.P. ; Minnis, A.M. ; Moncalvo, J.M. ; Mule, G. ; Nakasone, K.K. ; Niskanen, T. ; Olariaga, I. ; Papp, T. ; Petkovits, T. ; Pino-Bodas, R. ; Powell, M.J. ; Raja, H.A. ; Redecker, D. ; Sarmiento-Ramirez, J.M. ; Seifert, K.A. ; Shrestha, B. ; Stenroos, S. ; Stielow, B. ; Suh, S.O. ; Tanaka, K. ; Tedersoo, L. ; Telleria, M.T. ; Udayanga, D. ; Untereiner, W.A. ; Dieguez Uribeondo, J. ; Subbarao, K.V. ; Vagvolgyi, C. ; Visagie, C. ; Voigt, K. ; Walker, D.M. ; Weir, B.S. ; Weiss, M. ; Wijayawardene, N.N. ; Wingfield, M.J. ; Xu, J.P. ; Yang, Z.L. ; Zhang, N. ; Zhuang, W.Y. ; Federhen, S. - \ 2014
    Database : the Journal of Biological Databases and Curation 2014 (2014). - ISSN 1758-0463 - 21 p.
    internal transcribed spacer - arbuscular mycorrhizal fungi - ribosomal dna - interspecific hybridization - sequence analyses - species complex - identification - evolution - barcode - life
    DNA phylogenetic comparisons have shown that morphology-based species recognition often underestimates fungal diversity. Therefore, the need for accurate DNA sequence data, tied to both correct taxonomic names and clearly annotated specimen data, has never been greater. Furthermore, the growing number of molecular ecology and microbiome projects using high-throughput sequencing require fast and effective methods for en masse species assignments. In this article, we focus on selecting and re-annotating a set of marker reference sequences that represent each currently accepted order of Fungi. The particular focus is on sequences from the internal transcribed spacer region in the nuclear ribosomal cistron, derived from type specimens and/or ex-type cultures. Re-annotated and verified sequences were deposited in a curated public database at the National Center for Biotechnology Information (NCBI), namely the RefSeq Targeted Loci (RTL) database, and will be visible during routine sequence similarity searches with NR_prefixed accession numbers. A set of standards and protocols is proposed to improve the data quality of new sequences, and we suggest how type and other reference sequences can be used to improve identification of Fungi.
    Modelling the future of Boswellia papyrifera population and its frankincense production
    Lemenih, M. ; Arts, B.J.M. ; Wiersum, K.F. ; Bongers, F. - \ 2014
    Journal of Arid Environments 105 (2014). - ISSN 0140-1963 - p. 33 - 40.
    economic-systems - metema district - dry forest - tree size - land-use - ethiopia - stella - cover
    Sustainable production of the aromatic forest product frankincense is at stake due to rapid decline in its resource base. This affects livelihoods of thousands of citizens and several global industries. A system dynamic model approach is used to predict the future population of Boswellia papyrifera trees and its frankincense yield for three decades (2010e2040) in Metema and Abergelle districts in northern Ethiopia. Data from studies on the ecology, distribution, rate of deforestation and participatory future scenario development were put together and analysed using a model platform developed with STELLA. Four alternative scenarios namely Business As Usual (BAU); Low Intervention Scenario (LS), High Intervention Scenario (HS) and Stabilization Scenario (SS) were used. The model predicts 3%, 8% and 37% of the current stem population to exist in 2040 under BAU, LS, HS scenarios, respectively in Metema. Similarly, 11%, 13% and 46% stem density is predicted under BAU, LS and HS, respectively for Abergelle. Test of model sensitivity shows adult mortality is the most serious problem facing the resource. Immediate management intervention should focus on reducing adult tree mortality followed by reducing deforestation. Medium and long term interventions need to focus on how to improve recruitment and afforestation/reforestation of the species.
    Machbarkeits des "Comfort Class"-Konzepts (Proof of Principle of the Comfort Class Concept)
    Houwers, H.W.J. ; Greef, K.H. de; Vermeer, H.M. - \ 2011
    In: Proceedings of the 10. InternationalTagung "Bau, Technik und Umwelt in der landwirtschaftlichen Nutztierhaltung", 27-29 Sept. 2011, Kiel, Deutschland. - - p. 47 - 54.
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